Retinal sensitivity in healthy Indians using microperimeter

Structural and functional characterization of retinal impairment in T1DM patients without diabetic retinopathy: a 3-year longitudinal study

PURPOSE

To analyze the progression of structural and functional retinal impairment in type 1 diabetes mellitus (T1DM) patients with no clinical signs of diabetic retinopathy (DR) during a 3-year follow-up.

METHODS

This was an observational longitudinal study. Post-pediatric T1DM patients without clinical signs of DR, and sex- and age-matched healthy subjects were recruited at San Raffaele Hospital (Milan, Italy). Each patient underwent a comprehensive ophthalmological evaluation, including optical coherence tomography (OCT), OCT-angiography (OCT-A), retinal static and dynamic vessel analysis (DVA), and microperimetry.

RESULTS

21 eyes of 21 T1DM patients (10 females; 24 ± 2 years old), and 21 age and sex-matched healthy subjects were enrolled. At baseline, T1DM eyes revealed a significantly decreased vessel length density using OCT-A (p < 0.001 and p = 0.046 in 3 × 3 and 6 × 6 mm images) and a significantly increased vessel density index (p = 0.013 and p = 0.087 in 3 × 3 and 6 × 6 mm images) of deep capillary plexus. DVA detected a significantly decreased vessel response to flicker light (p = 0.002). A significantly increased thickness of ganglion cellular layer 6-mm-diameter subfields in inferior and superior quadrants was found in diabetic patients (p < 0.001 in both subfields). At 3-years-follow-up no significant longitudinal changes were disclosed in all analyses.

CONCLUSIONS

Concomitant subclinical microvascular and neurodegenerative damages could be early signs of DR onset that precede functional alterations and clinical signs of DR development. These alterations demonstrated a stable trend over time.

Fotopic and scotopic retinal sensitivity and foveal fixation normal values using microperimetry in healthy population

PURPOSE

To determine normal values of fotopic and scotopic retinal sensitivity and foveal fixation obtained by microperimetry, using MP3-S microperimeter (Nidek, Gamagori, Japan), in a healthy population.

METHODS

Observational, crossectional, single centre study. Fotopic and scotopic microperimetry was performed using with a customized 13-point fovea-centered pattern in healthy volunteers without ocular pathology. A intraclass correlation coefficient (ICC) was performed to evaluate fotopic and scotopic microperimetry reliability.

RESULTS

We analyzed 102 eyes of 54 patients with a mean age of 49.8 +/- 15 years old. The fotopic and scotopic mean retinal sensitivity (MRS) was 28.55±3.3dB (95% CI=[27.87-29.23]) and 15.72±1.9dB (95% CI=[15.35-16.09]) respectively, showing a significant statistical difference (p<0.05). No differences were found when comparing SRM by gender group. However, when analyzing the SRM by age groups, statistically significant differences were found in both modalities of the test; SRM being higher in the group of subjects under 35 years of age with 30.3±1.7dB in the photopic and 16.3±1.3dB in the scotopic; and lower in the group of older than 65 years with 26.7±2.2dB in the photopic and 13.8±1.8dB in the scotopic with p=0.0001. The reliability analysis of both tests, revealed an excellent reliability of the fotopic microperimetry with a Crombach alpha of 0.958 and a good reliability of 0.841 in scotopic microperimetry.

CONCLUSIONS

Microperimetry is a test with good reliability both under photopic and scotopic conditions. SRM and fixation stability under photopic and scotopic conditions do not differ according to sex, but it does decrease with age. There is a positive correlation between photopic and scotopic SRM.

Association between visual function and the integrity of residual ellipsoid zone in resolved central serous chorioretinopathy

Central serous chorioretinopathy (CSC) usually resolves spontaneously; however, in some patients, it can be chronic and visual impairment remains even after resolution of the serous retinal detachment. The impaired photoreceptor cells often present with disrupted ellipsoid zone (EZ) on optical coherence tomography (OCT). In this study, the integrity of EZ was quantified by calculating the index of residual EZ, identified on binarized OCT images from 25 eyes of 23 patients with resolved CSC. To estimate residual EZ, integrity of residual EZ with the central horizontal line on the fovea (rEZc) and average integrity of residual EZ within 3 × 3-mm macular area (rEZave) were investigated. The interrater reliability of the method was assessed using the intraclass correlation coefficient (ICC). The relationship between LogMAR VA and age, central retinal thickness, central choroidal thickness, rEZc, and rEZave were evaluated using the linear mixed model. Retinal sensitivity was measured with the MP-3 microperimeter and similar analyses were iterated for mean retinal sensitivity (MS). ICC values were 0.938 with rEZc and 0.979 with rEZave. rEZc was significantly related to LogMAR VA (p = 0.039). rEZave was significantly related to MS (p < 0.001). These results suggested potential usefulness of residual EZ to predict visual function in resolved CSC.

Effect of Age, Sex, Stimulus Intensity, and Eccentricity on Saccadic Reaction Time in Eye Movement Perimetry

Purpose

In eye movement perimetry (EMP), the extent of the visual field is tested by assessing the saccades using an eye tracker. The aim of the present study was to determine the effects of age and sex of the subjects, the eccentricity and intensity of the peripheral stimuli on saccadic reaction time (SRT), and the interaction between these parameters in healthy participants.

Methods

Healthy participants aged between 20 to 70 years underwent a complete ophthalmic examination and an EMP test. SRT was determined from detected peripheral stimuli of four intensity levels. A multilevel mixed-model analysis was used to verify the influence of subject and stimulus characteristics on SRT within the tested visual field.

Results

Ninety-five subjects (mean age 43.0 [15.0] years) were included. Age, stimulus intensity, and eccentricity had a statistically significant effect on SRT, not sex. SRTs were significantly faster with increasing stimulus intensity and decreasing eccentricity (P < 0.001). At the lowest stimulus intensity of 192 cd/m², a significant interaction was found between age and eccentricity.

Conclusions

The current study demonstrated significant SRT dependence across the visual field measured up to 27°, irrespective of sex. The presented SRT values may serve as a first normative guide for EMP.

Translational Relevance

This report of SRT interaction can aid in refining its use as a measure of visual field responsiveness.

Microperimetry - A New Tool for Assessing Retinal Sensitivity in Macular Diseases

INTRODUCTION

Macular disease is the leading cause of low vision in the Western world. Drusen and pigmentary irregularities are common among the rural Northern Indian population. The disease process leads to loss of central vision, metamorphopsia, macropsia or micropsia and colour vision defect.

AIM

To study the retinal sensitivity changes in macular diseases using microperimetry.

MATERIALS AND METHODS

It was an observational study, conducted in the Department of Ophthalmology at a rural tertiary care hospital. This study was started from December 2014 until June 2016, in all patients with macular disease above the age of 20 years attending the outpatient department. Microperimetry was done for 84 eyes of 52 patients with macular disease. Mean retinal Sensitivity (MS) and fixation stability was evaluated. The statistical analysis of mean retinal sensitivity, central 2° and 4° fixation was done by calculating the mean and standard deviation using 95% confidence interval.

RESULTS

The range of age was between 20-81 years. Majority were 32 males (62%) and 20 females (38%). Out of the 84 eyes studied, majority of the macular disease were Age-Related Macular Degeneration (AMD) (50%). Rest 50% were other macular diseases. The mean retinal sensitivity (dB) shown by microperimetry was 10.83 in AMD, 9.12 in Cystoid Macular Oedema (CME), 10.34 in Epiretinal Membrane (ERM), 10.74 in Pigment Epithelial Detachment (PED), 8.96 in Central Serous Chorioretinopathy (CSCR), 6.43 in macular dystrophy, 7.15 in Lamellar Hole (LMH), 9.8 in Pseudomacular Hole (PMH), 3 in geographic atrophy, 11.1 in macular telangiectasia, 5.6 in Berlin oedema, 12.3 in macular scar and 15.2 in haemorrhage in macula. The study showed 64% of the eyes had stable 2° central fixation, 35% had relatively unstable fixation and 1% had unstable fixation. No significant correlation between retinal sensitivity and retinal thickness in AMD was found.

CONCLUSION

This study shows that microperimetry can be a useful tool for objective evaluation of macular function and progression of the disease.

Normal values for microperimetry with the MAIA microperimeter: sensitivity and fixation analysis in healthy adults and children

PURPOSE

To establish normative values of retinal sensitivity and parameters describing the fixation pattern using macular analyzer integrity assessment (MAIA) microperimetry (Centervue, Padova, Italy) in adults and children.

METHODS

A sample of 237 eyes of 237 healthy subjects aged between 10 and 70 years (mean age 30.63 ± 16.23 years) was evaluated using the MAIA microperimeter. The following parameters provided by the MAIA device were evaluated: average threshold (AT), macular integrity, fixation indexes (P1% and P2%), bivariate contour ellipse area (BCEA) for 95% and 63% of points, and horizontal (H) and vertical (V) axes of the ellipse of fixation. Differences between different age-related groups were evaluated. Correlation of microperimetric parameters with age was also assessed.

RESULTS

Median retinal sensitivity of the overall sample was 32.90 dB (interquartile range 1.80 dB). Median P1 and P2 values were 98.00% (6.00) and 100.00% (1.00), respectively. Median BCEA for 95% and 63% of points were 2.40°2 (4.50) and 0.30°2 (0.50), respectively. Median H and V were 0.90° (0.80) and 0.90° (0.70), respectively. Age was significantly correlated with the following parameters in subjects from 21 to 70 years of age (p<0.01): AT (rho -0.47), P1 (rho -0.37), BCEA95 (rho 0.43), BCEA63 (rho 0.42), H (rho 0.43), and V (rho 0.40).

CONCLUSIONS

Retinal sensitivity in healthy eyes tends to decrease with age as well as the stability of the pattern of fixation. A normative database in terms of retinal sensitivity threshold and fixation performance can be established in this type of eyes.

Retinal sensitivity in subjects with type 2 diabetes mellitus: Sankara Nethralaya Diabetic Retinopathy Epidemiology and Molecular Genetics Study (SN-DREAMS II, Report No. 4)

AIM

To evaluate retinal sensitivity (RS) in subjects with diabetes in a population-based study and to elucidate associated risk factors for abnormal RS.

METHODS

A subset of 357 subjects from Sankara Nethralaya Diabetic Retinopathy Epidemiology and Molecular Genetics Study-II was included in this study. All subjects underwent detailed ophthalmic evaluation including microperimetry and spectral domain optical coherence tomography.

RESULTS

The prevalence of abnormal mean retinal sensitivity (MRS) was 89.1%. MRS was significantly reduced in subjects with diabetes but no retinopathy when compared with non-diabetic subjects. MRS was reduced in moderate non-proliferative diabetic retinopathy (DR) and macular oedema (ME) at 8° (p=0.04, p=0.01, respectively) and in ME at 10° (p=0.009) and 12° (p=0.036) compared with no DR. Significant negative correlation was found between MRS and best corrected visual acuity, duration of diabetes, glycosylated haemoglobin and central foveal thickness. Increased retinal thickness remained a significant risk factor (OR, 1.02; p=0.044) for abnormal MRS. Altered inner retinal layers and foveal contour were associated with reduced MRS among subjects with DR and presence of epiretinal membrane, altered foveal contour and altered retinal pigment epithelium were associated with reduced MRS.

CONCLUSIONS

Reduced RS in those subjects with diabetes but no retinopathy suggests the early neuronal damage in type 2 diabetes mellitus.